More particularly, the invention relates to a wringer in the form of an annular sleeve which comprises:                an upper section designed to be secured by interlocking into the neck of a reservoir of product (liquid or paste), said upper section having a first inscribed circle diameter,        a free lower section having a second inscribed circle diameter that is less than the first inscribed circle diameter,        an intermediate section which forms an inwardly projecting annular crease delimiting a central throat having a third inscribed circle diameter which is at least equal to the second inscribed circle diameter in the rest position, and said annular crease being deformable, by axial compression between the upper and lower sections, to a wringing position in which the central throat is smaller than in the rest position, said central throat having in said wringing position a fourth inscribed circle diameter which is less than the second and third inscribed circle diameters.        
Document JP-U-60 14351 describes an example of a wringer of this type, intended for a mascara container assembly, which comprises several annular creases and has the disadvantage that the inside of the annular creases rapidly fills with mascara, which deposits there and then prevents said creases from deforming. The wringer becomes clogged by the deposited mascara, interfering with its operation.
In general, in fluid product packaging assemblies having a wringing means, this clogging phenomenon due to deposited product also occurs in the neck, because generally the upper portion of the wringer squeezes the applicator head relatively significantly when said applicator head is reintroduced into the reservoir, leaving deposited product at the neck of the reservoir. This other route to clogging the neck and the upper portion of the wringer is particularly detrimental to the product life, because eventually there is no longer a proper seal at the neck and the product quality is substantially degraded. It can also make it difficult to open the cap.